text: // Arguments: Doubles, Doubles, Doubles
  #include <stan/math/prim/scal.hpp>
  
  using stan::math::var;
  using std::numeric_limits;
  using std::vector;
  
  class AgradCdfLogInvGamma : public AgradCdfLogTest {
   public:
    void valid_values(vector<vector<double> >& parameters,
                      vector<double>& cdf_log) {
      vector<double> param(3);
  
      param[0] = 3.0;  // y
      param[1] = 0.5;  // alpha (Shape)
      param[2] = 3.3;  // beta (Scale)
      parameters.push_back(param);
      cdf_log.push_back(
          std::log(0.138010737568659559638900550956));  // expected cdf_log
    }
  
    void invalid_values(vector<size_t>& index, vector<double>& value) {
      // y
      index.push_back(0U);
      value.push_back(-1.0);
  
      // alpha
      index.push_back(1U);
      value.push_back(-1.0);
  
      index.push_back(1U);
      value.push_back(0.0);
  
      index.push_back(1U);
      value.push_back(numeric_limits<double>::infinity());
  
      // beta
      index.push_back(2U);
      value.push_back(-1.0);
  
      index.push_back(2U);
      value.push_back(0.0);
  
      index.push_back(2U);
      value.push_back(numeric_limits<double>::infinity());
    }
  
    bool has_lower_bound() { return true; }
  
    double lower_bound() { return 0.0; }
  
    bool has_upper_bound() { return false; }
  
    template <typename T_y, typename T_shape, typename T_scale, typename T3,
              typename T4, typename T5>
    typename stan::return_type<T_y, T_shape, T_scale>::type cdf_log(
        const T_y& y, const T_shape& alpha, const T_scale& beta, const T3&,
        const T4&, const T5&) {
      return stan::math::inv_gamma_cdf_log(y, alpha, beta);
    }
  
    template <typename T_y, typename T_shape, typename T_scale, typename T3,
              typename T4, typename T5>
    typename stan::return_type<T_y, T_shape, T_scale>::type cdf_log_function(
        const T_y& y, const T_shape& alpha, const T_scale& beta, const T3&,
        const T4&, const T5&) {
      using stan::math::gamma_q;
  
      return log(gamma_q(alpha, beta / y));
    }
  };
  